Εξειδίκευση τύπου :	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	Anomalous Deformation Behavior in ULE Glass upon Microindentation: A Vibrational Spectroscopic Investigation in the Induced Structural Changes of a Ti-Silicate Glass
Δημιουργός/Συγγραφέας:	Möncke, Doris Lind, Felix Topper, Brian [EL] Καμίτσος, Ευστράτιος Ι.[EN] Kamitsos, Efstratios I.
Εκδότης:	American Chemical Society
Ημερομηνία:	2021
Γλώσσα:	Αγγλικά
ISSN:	1932-7447 1932-7455
DOI:	10.1021/acs.jpcc.0c09865
Περίληψη:	Ultralow expansion (ULE) glass, a binary TiO2–SiO2 glass with 5.67 mol % TiO2, was exposed to microindentation. Vitreous silica was similarly treated and used as a reference material, including the characterization of mechanical properties by means of ultrasonic echography and nanoindentation. The structural modifications induced by indentation were analyzed by micro-Raman spectroscopy. The observed structural changes are consistent with an anomalous, densification-driven, deformation mechanism similar to those observed for vitreous silica or commercially relevant low alkali borosilicate glasses like Duran. As for these fully polymerized glasses, the Raman spectra of indents in the ULE glass are characterized by an upshift of the 407 cm–1 band and an increase in the intensity of the D1 and D2 defect bands, all consistent with structural rearrangements from mostly larger five- and six-member rings to a larger population of smaller four- and three-member rings and an overall lowering of the free volume in the glass. However, contrary to silicon, titanium may change its coordination number under the impact of microindentation. Raman spectra of selected reference materials such as TiO2 and BaTiO3, with known octahedral titanium coordination and known connectivity, as well as fresnoite Ba2TiSi2O8 with known fivefold Ti4+ coordination, are therefore included in this study in support of assigning the new activity appearing in the Raman spectra after an indentation of the ULE glass sample.
Τίτλος πηγής δημοσίευσης:	The Journal of Physical Chemistry C
Τόμος/Κεφάλαιο:	125
Τεύχος:	7
Σελίδες:	4183–4195
Θεματική Κατηγορία:	[EL] Φυσική και θεωρητική χημεία[EN] Physical and theoretical chemistry [EL] Φασματοσκοπία[EN] Spectroscopy
Λέξεις-Κλειδιά:	Amorphous materials Anions Oxides Raman spectroscopy Titanium
EU Grant identifier:	MO1375/3-1 57161434 MIS 5002772 NSRF 2014-2020
Κάτοχος πνευματικών δικαιωμάτων:	© 2021 American Chemical Society
Σημειώσεις:	We gratefully acknowledge financial support through the Priority Program 1594 of the German Science Foundation under Grant No. MO1375/3-1 and through the joint DAADIKYDA 2015 program for fostering exchange between German and Greek universities (Grant No. 57161434). E.I.K. also acknowledges support by the project “National Infrastructure in Nanotechnology, Advanced Materials and Micro-/Nanoelectronics” (MIS 5002772), funded by the Operational Program “Competitiveness, Entrepreneurship and Innovation” (NSRF 2014-2020) and cofinanced by Greece and the European Union (European Regional Development Fund). Most of the experiments on ULE have been conducted at the NHRF in Athens, Greece and, for reference materials, at Alfred University. Part of this material (Raman data) is based upon work supported by the National Science Foundation under Grant No. DMR-1626164. Indentation and mechanical testing was conducted at the Otto-Schott-Institute of Materials Research at the Friedrich-Schiller University in Jena, Germany, when F.L. and D.M. were members of the glass group of L. Wondraczek. For helpful discussions and/or experimental help, we thank I. Efthimiopoulos, D. Ehrt, J. Hunt, D. Palles, R. Limbach, and F. Zimmermann.
Εμφανίζεται στις συλλογές:	Ινστιτούτο Θεωρητικής και Φυσικής Χημείας (ΙΘΦΧ) - Επιστημονικό έργο